Returning to parliament today after the summer recess and the party conference season, MPs and peers may be surprised to learn that a written constitution has been prepared in their absence. There have been vague murmurs from Gordon Brown and Jack Straw over the last year or so that some sort of codification might be desirable, in light of the constitutional reforms introduced since 1997. And for a month or two this summer, when public anger about MPs' expenses was at its peak, the case for a written constitution was quite possibly being more widely discussed, including at a government level, than at any time in British political history. But surely nobody suggested that anyone should actually go ahead and draft one?

The written constitution in question is a spoof. Led by my colleague at Democratic Audit, Stuart Weir, and in association with a wider network of expert contributors, our pamphlet The Unspoken Constitution sets out to describe our constitutional arrangements as they work in practice. We determined early on to adopt a satirical tone, inviting the reader to chuckle at the hilarity of it all – the extensive powers of the monarch, which monarchs implicitly promise not to use; the even more extensive royal prerogative powers granted to prime ministers by the Crown, so that governments can take major decisions without recourse to parliament; the myth that parliament is sovereign, when its powers have been progressively eroded over decades; and the fact that basing constitutional practice on conventions means that governments can essentially amend the constitution simply by changing how they go about their business.

While we hope the text will be seen as genuinely funny – to political insiders at least – our overriding purpose is to offer a serious critique of our democratic arrangements. This critique, compressed into 14 constitutional articles, aims to expose the rotten character of a political system that blends the continuation of ancient pre-democratic practices with modern anti-democratic measures designed to maximise the powers of a prime minister through the fusion of the executive and legislative branches of government. Rather than commencing "we, the people", as the US and other constitutions do, our version opens with "we, the elite", in recognition that it is the myth of parliamentary sovereignty, rather than the ideal of popular sovereignty, that underpins the UK constitutional order. We seek to lay bare the constitutional realities our governing elite would go to any lengths to disguise. Hence the document's title – ours is an unspoken, rather than an unwritten, constitution.

The case for root-and-branch reform of our political system has been made so often, and so convincingly, that there is no need to repeat it. The great wave of public anger about expenses reinforces that this is not an issue for the chattering classes. However, there is an obvious constituency that remains largely oblivious to such demands: returning from the recess, most MPs are clearly hoping we can return to political life as it was pre-expenses. The virtual absence of debate about the need for urgent democratic reform during the party conferences underlines the wider complacency of our political parties, who are hoping that we can return to business as usual, with an election looming ever closer.

The need to force the debate about reform onto the general election agenda has led the two Joseph Rowntree Trusts to re-launch the Power inquiry as Power2010. Over the next few months, Power 2010 will be encouraging any UK citizen to submit his or her own proposals for political reforms. These proposals will ultimately be debated by randomly selected participants and then be put to a popular vote to ascertain which five reforms the British public would most like to see. Every candidate at the 2010 general election will be invited to endorse these popular demands for democratic reform. As yet, we have no idea what those demands may be – this is for "we, the people" to determine over the coming weeks and months. But in light of what The Unspoken Constitution reveals about how we are governed, it would be extraordinarily unwise for our future elected representatives to dismiss them out of hand.